"Esprit Rude/Esprit Doux" for flute and clarinet was composed for the celebration of Pierre Boulez's 60th birthday on March 31, 1985 in Baden-Baden. The title, translated as "rough breathing/smooth breathing", refers to the pronunciation of classical Greek words beginning with a vowel or an “R”. With “Esprit Rude” (rough breathing) the initial vowel (or "R") is to be preceded by a sounded "H", and is indicated by a reversed comma above the letter. With "Esprit Doux" (smooth breathing) the initial vowel is not to be preceded by "H" and is indicated by a comma above the vowel. In the Greek for "sixtieth year" (transliterated as "hexèkoston etos") the initial epsilon of the first word has a rough breathing sign while the epsilon of the second has a smooth one.